Asphalt Cement Grade Bitumen (AC)
The penetration grades bitumen is a kind of blown bitumen which is produced by different viscosity. It is graded based on its performance at different temperatures. In fact, penetration grade bitumen is a classification system used to specify the hardness or consistency of bitumen based on its penetration value.
The Long-Term Pavement Performance (LTPP) has given a certain algorithm to calculate the temperature of the pavement based on the temperature of the air above.
Bitumen penetration degree is the amount of length that a standard needle with a certain shape penetrates under the effect of a load equivalent to 100 grams in 5 seconds in bitumen at a temperature of 25° C.
This classification helps in determining the suitability of bitumen for various applications, particularly in road construction and pavement design. Higher penetration values indicate softer bitumen, while lower penetration values indicate harder bitumen.
The choice of penetration grade depends on factors such as climate, traffic load, and pavement design. Softer bitumen (higher penetration values) are more flexible and better suited for cooler climates, while harder bitumen (lower penetration values) are preferred in hot climates to resist deformation under high temperatures.
The common penetration grades used in road construction include:
- 30/40
- 40/50
- 50/70
- 60/70
- 70/100
- 80/100
- 100/120
For example penetration grade 60/70 is a medium-hard bitumen, which its penetration is in the range 60 to 70 mm at 25° C, suitable for general road construction in moderate climates. This is the one that is utilized the most frequently and a perfect choice for roads in various regions, particularly Asia and South East Africa.
Penetration grade 40/50 is harder than 60/70, suitable for general road construction in tropical areas. Penetration Grade 80/100 is slightly softer than 60/70, this grade is used in regions with relatively low temperatures and Penetration Grade 100/120 is soft bitumen and is used in regions with low temperatures.